Several hardware and design options exist for providing high energy pulsed current, but many of these options are deficient. Many are generally evolved, in one form or another, from older flyback type electronic power supply topologies that employ more modern switching techniques and digital controls to transform energy from low voltage DC to high voltage pulsed AC. Others involve more modern systems that employ magnetic compression techniques or drift field diodes to create unipolar high voltage pulses. The need for high pulse repetition rates, short pulse widths, and more sophisticated electronic biasing of the powered devices has strained the capabilities of traditional high voltage wire wound transformers used in flyback type devices. The useful performance envelope for flyback systems has been extended from the millisecond into the micro-second pulse-width range by employing methods that rely on resonance or dynamic resonance to pump charge into a single “discharge event” using several shorter, faster pulses. This approach is effective in generating high voltage pulses in the micro-second pulse-width range at the expense of introducing some undesirable conditions for processes that seek to produce lower temperature ions with refined post-pulse ion treatment requirements. These enhancements also fall short in applications in which there is need to avoid the formation of micro channels in the plasma discharge which can lead to localized heating and damage to dielectrics as well as undesirable energy distributions for some non-thermal plasma processes. All these issues constrain the designs of plasma devices to materials that support good heat transfer, high dielectric strength and high thermal stability.
The issues identified above are greatly ameliorated by employing non-thermal plasma power supplies that deliver the energy in high voltage pulses that are in the nanosecond or tens of nanoseconds time range. This need for pulse widths in the nanosecond time range to drive next-generation devices at very precise levels of control is developing and so are the options for providing the very short, high energy pulses they require. More specifically, designs utilizing Blumlein pulse-forming lines or pulse-forming networks, Marx and vector inversion generators, drift-field diode devices, or magnetic compression generators are well documented and shown to be effective.
Each of these approaches has merit in some applications and deficiencies when applied to others. In the application to non-thermal high pressure plasmas, all present significant challenges involving, to one extent or another, cost and complexity, ability to tune to load variations, or undesirable situations for switching electronics. In practical non-thermal plasma applications, it is typically desirable to employ electronic power supplies capable of delivering high voltage pulses that have pulse widths in the sub-100 nanosecond time range to minimize the energy transfer to ions in the form of heat. Several technologies that provide pulses with peak voltage in the kilovolt range and pulse widths on the order of 1-10 nanoseconds have been disclosed previously. Devices utilizing inductive adders or drift field diodes have been demonstrated, however existing designs tend to be relatively expensive and, at the same time, do not always provide a good solution for high-density ion generation application, as they are providing pulses that are unipolar, or may be shorter in duration than is required and are not configurable. Devices utilizing magnetic compression effects are effective in delivering the desired pulsed energy but are not amenable to applications which benefit from a broad bandwidth (frequency range) output.
Typical pulsed power supply devices in the inductive adder class seek to provide single polarity pulses with very little overshoot and very short pulse widths (1-10 nanoseconds) and do so by limiting both the primary and secondary turns to one. These supplies were targeted primarily at applications involving high energy physics such as lasers or ion accelerators. The turns ratio of 1:1 is employed to achieve the shortest possible pulse widths, but results in the need for either a larger number of cores or a higher primary side drive voltage, or both.
This background discussion is intended to provide information related to the present invention which is not necessarily prior art.